Polyfluoroalkyl allyl compound and method for producing the same

ABSTRACT

(n, a, and b are as defined above, and R′: a C1-C3 alkyl group) with a transition metal. This method for producing provides a polyfluoroalkyl allyl compound used as a synthetic intermediate for a fluorine-containing alkylsilane compound that can remove free iodine derived from the raw material compound, before a hydrosilylation reaction is performed, without using a metal reagent having a high environmental impact, and that has excellent handling properties.

TECHNICAL FIELD

The present invention relates to a polyfluoroalkyl allyl compound and a method for producing the same. More particularly, the present invention relates to a polyfluoroalkyl allyl compound that is used as a synthetic intermediate for a fluorine-containing alkylsilane compound having a high water contact angle, and a method for producing the same.

BACKGROUND ART

In general, compounds having a perfluoroalkyl group as a structural unit are known to improve surface modifying properties, water- and oil-repellency, mold releasability, antifouling properties, leveling properties, etc., of various substrates, such as fiber, metal, glass, rubber, and resin, by chemical treatment of the surface of each substrate.

Among such compounds, telomer compounds containing a perfluoroalkyl group having 8 to 12 carbon atoms are most likely to exhibit the above properties. Telomer compounds having 8 carbon atoms are preferably used.

However, it has been recently reported that perfluorooctanoic acid having 8 carbon atoms or perfluorocarboxylic acids having more than 8 carbon atoms have adverse effect on the environment, because they have low degradability and high bioaccumulation potential, and there is suspicion of biological toxicity. Among these compounds, those containing a perfluoroalkyl group having more than 8 carbon atoms are suggested to be possibly converted to perfluorooctanoic acid or perfluorocarboxylic acids having more than 8 carbon atoms by biodegradation or chemical degradation in the environment, and there is concern that it will become difficult to produce and use those compounds for the future. However, compounds containing a perfluoroalkyl group having 6 or less carbon atoms are said to have low bioaccumulation potential.

Fluorine-containing alkylsilane compounds containing a perfluoroalkyl group having 6 or less carbon atoms and having a high water contact angle are also known.

Patent Document 1 discloses a method for obtaining a fluorine-containing alkylsilane compound having terminal —CH₂CH₂Si(R¹)_(3-n)X_(n) by reducing, with a reducing agent, a compound obtained by an addition reaction of R^(F)(CH₂CH₂)_(a)(CH₂CF₂)_(b)(CF₂CF₂)_(c)I with CH₂═CHSi(R¹)_(3-n)X_(n).

In this method, however, iodine is desorbed in the final step, and there is thus a concern about coloring of the target compound with iodine. In addition, there is a problem that hydrogenated tributyltin and the like that have a high environmental load are used in the deiodination reaction. Moreover, it is described that a compound having a CH₂ group between a CF₂ group and a CF₂ group is weak under basic conditions, which means that the reaction conditions (synthetic route) are limited.

Patent Document 2 indicates that silane coupling agents having a biphenyl alkyl group Rf(C₆H₄—C₆H₄)CH₂CH₂CH₂Si(OCH)₃ are compounds having excellent heat resistance, durability, mold releasability, and antifouling properties, so that the contact angle of surfaces modified by these compounds are not reduced even after exposure to an atmosphere at a high temperature of 350° C. or more.

However, these compounds are solids at ordinary temperature because of the biphenyl skeleton in their molecules, and may be thus difficult to handle. Further, organic lithium, such as n-butyllithium, is used as a reaction reagent. This is a highly reactive and water-prohibiting regent. It is thus necessary to slowly drop such a reagent under low temperature conditions, since, for example, control of the reaction heat during the reaction becomes necessary. Thus, handling properties are poor, and the process used therein is not suitable for large-scale production.

A fluorine-containing alkylsilane compound having a bifunctional organosiloxane group is described in Patent Document 3.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP-A-2014-40373

Patent Document 2: WO 2008/108438 A1

Patent Document 3: JP-A-2009-137842

Patent Document 4: JP-B-5292826

OUTLINE OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to provide a polyfluoroalkyl allyl compound used as a synthetic intermediate for a fluorine-containing alkylsilane compound that can remove free iodine derived from the raw material compound, before a hydrosilylation reaction is performed, without using a metal reagent having a high environmental impact, and that has excellent handling properties; and to also provide a method for producing the same.

Means for Solving the Problem

The present invention provides a polyfluoroalkyl allyl compound represented by the general formula:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)CH₂CH═CH₂  [I]

wherein n is an integer of 0 to 5, a is 1 or 2, and b is an integer of 0 to 3.

The polyfluoroalkyl allyl compound is produced by reacting a carboxylic acid allyl adduct represented by the general formula:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)CH₂CHICH₂OCOR′  [II]

wherein n, a, and b are as defined above, and R′ is a C₁-C₃ alkyl group, with a transition metal.

Effect of the Invention

The polyfluoroalkyl allyl compound of the present invention is used as a reaction raw material (synthetic intermediate), and a fluorine-containing alkylsilane compound having a terminal —SiR_(3-d)X_(d) group can be produced by reacting it with alkoxysilane using a transition metal catalyst, or by reacting it with chlorosilane, followed by a reaction with lower alcohol or metal alkenyl. In this reaction, free iodine derived from the raw material compound can be removed before a hydrosilylation reaction is performed, and handling properties are excellent. Moreover, a fluorine-containing alkylsilane compound to which a suitable hydrosilylating agent is added can be chemically bonded to the surface of various substrates, thereby imparting water- and oil-repellency, antifouling properties, etc., thereto.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

The polyfluoroalkyl allyl compound of the present invention and the fluorine-containing alkylsilane compound produced by using the polyfluoroalkyl allyl compound of the present invention as a reaction raw material (synthetic intermediate) are produced through the following series of steps:

(1) A Compound:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)I  [III]

is reacted with carboxylic acid allyl ester R′COOCH₂CH═CH₂.

(2) The Resulting Product:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)CH₂CHICH₂OCOR′  [II]

is reacted with a transition metal.

(3) The Resulting Product:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)CH₂CH═CH₂  [I]

is reacted with alkoxysilane, or reacted with chlorosilane, followed by a reaction with C₁-C₃ lower alcohol or metal alkenyl, thereby obtaining the following compound:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)(CH₂)₃SiR_(3-d)X_(d)  [Iv].

Examples of C₁-C₃ lower alcohol usable herein include fluorine-free alcohols, such as methanol, ethanol, propanol, and isopropanol; and fluorine-containing alcohols, such as trifluoroethanol, tetrafluoropropanol, and hexafluoroisopropanol. Moreover, examples of metal alkenyl include allyl magnesium chloride, allyl magnesium bromide, and the like.

The polyfluoroalkyl iodide [III] used as a raw material compound in step (1) above is a known compound, and disclosed, for example, in Patent Document 4.

Specific examples of the polyfluoroalkyl iodide used include the following compounds:

CF₃(CF₂)(CH₂CF₂)I

CF₃(CF₂)(CH₂CF₂)₂I

CF₃(CF₂)₂(CH₂CF₂)I

CF₃(CF₂)₂(CH₂CF₂)₂I

CF₃(CF₂)₃(CH₂CF₂)I

CF₃(CF₂)₃(CH₂CF₂)₂I

CF₃(CF₂)(CH₂CF₂)(CF₂CF₂)I

CF₃(CF₂)(CH₂CF₂)(CF₂CF₂)₂I

CF₃(CF₂)₂(CH₂CF₂)(CF₂CF₂)I

CF₃(CF₂)₂(CH₂CF₂)(CF₂CF₂)₂I

CF₃(CF₂)₃(CH₂CF₂)₂(CF₂CF₂)I

CF₃(CF₂)₃(CH₂CF₂)₂(CF₂CF₂)₂I

As a slightly excess mole number of carboxylic acid allyl ester R′COOCH₂CH═CH₂ to be reacted with such a polyfluoroalkyl iodide, compounds, in which R′ has a C₁-C₃ alkyl group, preferably allyl acetate are used. This reaction is performed as a radical addition reaction at a temperature of about 70 to 120° C. in the presence of a radical initiator in an amount of about 0.001 to 1.0 mol % based on the polyfluoroalkyl iodide. Examples of the radical initiator include peroxydicarbonates, such as di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, di(2-ethoxyhexyl) peroxydicarbonate, di(3-methoxybutyl) peroxydicarbonate, and di-sec-butyl peroxydicarbonate.

The resulting carboxylic acid allyl adduct [II] is reacted with a transition metal, for example, a simple metal such as Zn, Mg, Mn, Cu or a reagent thereof, preferably simple Zn, as the reduction of iodine and olefination reaction. The carboxylic acid allyl adduct and the transition metal are each used together with a solvent, such as methanol and ethanol. Moreover, the transition metal is used in a slightly excess molar ratio based on the carboxylic acid allyl adduct.

The resulting polyfluoroalkyl allyl compound [I]:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)CH₂CH═CH₂

is reacted with an alkoxysilane to thereby yield:

CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)(CH₂)₃SiR_(3-d)X_(d)

Examples of alkoxysilane include trimethoxysilane, triethoxysilane, tripropoxysilane, and the like, having a C₁-C₃ lower alkoxy group. The alkoxysilane is used in slightly excess molar ratio based on the terminal allyl compound.

The reaction is performed at a reaction temperature of about 25 to 100° C. in the presence of a transition metal catalyst. Examples of transition metal catalysts, preferably Pt-based or Rh-based catalysts, include chloroplatinic acid H₂PtCl₁₆.6H₂O, Karstedt's catalyst Pt.CH₂═CHSiMe₂OMe₂OSiCH═CH₂, Wilkinson's catalysts RhCl[P(C₆H₅)₃]₃, RhH[P(C₆H₅)₃]₄, and the like. The catalyst is used in an amount of about 0.001 to 10 mol % based on the polyfluoroalkyl allyl compound.

The polyfluoroalkyl allyl compound [I] can also be reacted with slightly excess molar ratio of chlorosilane, followed by a reaction with C₁-C₃ lower alcohol or metal alkenyl, thereby obtaining the target compound. The reaction with chlorosilane is performed using a transition metal catalyst as mentioned above at a ratio of about 0.001 to 10 mol % based on the polyfluoroalkyl allyl compound at a reaction temperature of about 25 to 100° C., and after imparting —SiCl₃ to a terminal group, the resultant is reacted with a C₁-C₃ lower alcohol or metal alkenyl at a reaction temperature of about 25 to 120° C. In this case, a lower alcohol or metal alkenyl can be reacted in an amount of less than 3 equivalents based on the terminal —SiCl₃ group, thereby allowing halogen to remain in the terminal group.

The obtained fluorine-containing alkylsilane compound has a high water contact angle, which indicates a low surface free energy, and therefore indicates high mold releasability, and high antifouling properties.

EXAMPLES

The following describes the present invention with reference to Examples.

Example 1

A 1000-ml three-necked flask was equipped with a dropping funnel and a Dimroth condenser in the presence of inert nitrogen gas. 400 g (0.66 mol) of polyfluoroalkyl iodide CF₃(CF₂)₃(CH₂CF₂)(CF₂CF₂)₂I was charged in the three-necked flask, while 74.0 ml (0.69 mol) of allyl acetate CH₂═CHCH₂OCOCH₃ and 2.61 g (6.5 mmol) of a radical initiator P-16 [di(tert-butylcyclohexyl) peroxydicarbonate] were placed in the dropping funnel, respectively, and the content of the three-necked flask was stirred. When the temperature reached 90° C., droppings from the dropping funnel was started to initiate reaction. Heat generation became weak in the latter half of the reaction; therefore, 0.09 g of P-16 was added to allow the reaction to continue.

Two hours later after completion of the heat generation, the temperature was cooled to room temperature. The reaction mixture was analyzed by NMR and gas chromatography to confirm the structure and conversion of the reaction product. The conversion of the target product was 87%. Unreacted raw material compounds were removed by vacuum distillation, thereby obtaining 391 g (95% GC, yield: 84%) of light yellow solid allyl acetate adduct.

CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂CHICH₂OCOCH₃

¹⁹F-NMR (d-acetone, 282.65 Hz):

-   -   −80.2:CF₃ CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −110.3:CF₃CF₂CF₂CF₂ CH₂CF₂ CF₂CF₂CF₂CF₂CH₂—     -   −112.2:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂ CH₂—     -   −120.2:CF₃CF₂CF₂CF₂CH₂CF₂CF₂ CF₂CF₂CF₂CH₂—     -   −121.9:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂ CF₂CF₂CH₂—     -   −122.5:CF₃CF₂CF₂ CF₂CH₂CF₂CF₂CF₂CF₂ CF₂CH₂—     -   −124.9:CF₃CF₂ CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—

Example 2

A 500-ml three-necked flask was equipped with a dropping funnel and a Dimroth condenser in the presence of inert nitrogen gas. 180 ml of methanol and 20.1 g (0.33 mol) of Zn were placed in the flask, while 200 g (0.28 mol) of the allyl acetate adduct obtained in Example 1 and 20 ml of methanol were placed in the dropping funnel, respectively, and the content of the three-necked flask was stirred. When reflux started to occur, droppings from the dropping funnel was started to initiate reaction. After dropping, the resulting mixture was stirred for 2 hours, and then cooled to room temperature to stop the reaction.

Since the phase separation of the reaction mixture was unclear, an attempt was made to cause liquid separation by distilling off the methanol; however, an emulsion was formed. Accordingly, the precipitate was filtered, followed by liquid separation again and drying, thereby obtaining 123.7 g (92% GC, yield: 77%) of the target compound, i.e., a transparent liquid terminal allyl compound. In this reaction, it was confirmed that the reaction proceeded with good reproducibility, irrespective of the purity of the starting material. Next, vacuum distillation was performed to increase the purity to 97% GC.

CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂CH═CH₂

¹H-NMR (d-acetone, 300.4 Hz):

-   -   δ5.9-5.7: —CF₂CH₂CH═CH₂(m)         -   5.4: —CF₂CH₂CH═CH ₂(m)         -   3.6: —CF₂CH ₂CF₂-(quin)         -   3.0: —CF₂CH ₂CH═CH₂(dt)

¹⁹F-NMR (d-acetone, 282.65 Hz):

-   -   −80.2:CF₃ CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −110.2:CF₃CF₂CF₂CF₂ CH₂CF₂ CF₂CF₂CF₂CF₂CH₂—     -   −111.9:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂ CH₂—     -   −120.3:CF₃CF₂CF₂CF₂CH₂CF₂CF₂ CF₂CF₂CF₂CH₂—     -   −121.9:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂ CF₂CF₂CH₂—     -   −122.1:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂ CF₂CH₂—     -   −122.5:CF₃CF₂CF₂ CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −124.9:CF₃CF₂ CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—

Reference Example 1

A 100-ml three-necked flask was equipped with a septum and a Dimroth condenser in the presence of inert nitrogen gas. 20.0 g (0.04 mol) of the terminal allyl compound obtained in Example 2 and 5.8 ml (0.05 mol) of triethoxysilane were placed in the three-necked flask. The content of the three-necked flask was stirred, and the temperature was increased to 80° C. After the temperature increase, 20 mg (0.05 mol % based on the terminal allyl compound) of chloroplatinic acid H₂PtCl₁₆.6H₂O was added to initiate reaction. After stirring for the whole day and night, the reaction mixture was cooled to room temperature to stop the reaction.

The reaction mixture was subjected to vacuum distillation, thereby obtaining 10.7 g (yield: 42%) of the target compound, i.e., a transparent liquid terminal triethoxysilylpropyl derivative.

CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂CH₂CH₂Si(OCH₂CH₃)₃

¹H-NMR (CDCl₃, 300.4 Hz):

-   -   δ3.83: —Si(OCH₂CH₃)₃(q)         -   2.92: —CF₂CH₂CF₂-(quin)         -   2.13: —CH₂CH₂CH₂-(tt)         -   1.75: —CH₂CH₂CH₂-(m)         -   1.21: —Si(OCH₂CH₃)₃(t)         -   0.70: —CH₂CH₂CH₂-(t)

¹⁹F-NMR (CDCl₃, 282.65 Hz):

-   -   −82.2:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −113.2:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −115.6:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −122.5:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −124.0 to −126.0:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −127.0:CF₃CF₂ CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—

Reference Example 2

A 100-ml three-necked flask was equipped with a septum and a Dimroth condenser in the presence of inert nitrogen gas. 20.0 g (0.04 mol) of the terminal allyl compound obtained in Example 2 and 4.8 ml (0.05 mmol) of trichlorosilane SiHCl₃ were placed in the three-necked flask. The content of the three-necked flask was stirred, and the temperature was increased to 40° C. After the temperature increase, 14.5 mg (0.1 mol % based on the terminal allyl compound) of Karstedt's catalyst (Pt.CH₂═CHSiMe₂OMe₂SiCH═CH₂) was added to initiate the reaction. The oil bath temperature was gradually increased. When the temperature reached 100° C., the temperature was maintained at a constant, and stirring was performed for the whole day and night. After the disappearance of raw materials was confirmed by NMR, the reaction was stopped by cooling the reaction mixture to room temperature.

Next, without purifying a terminal trichlorosilyl product produced by this reaction, 3.7 ml (0.05 mol) of methyl orthoformate CH(OCH₃)₃ was added thereto, and the mixture was heated to 40° C. After confirming that the reaction solution became homogeneous, 5.6 ml (0.15 mol) of methanol was added, and the mixture was stirred for 1 hour, followed by distilling off of low-boiling components and vacuum distillation, thereby obtaining 10.10 g (yield: 41%) of the target compound, i.e., a transparent liquid terminal trimethoxysilylpropyl derivative.

CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂CH₂CH₂Si(OCH₃)₃

¹H-NMR (CDCl₃, 300.4 Hz):

-   -   δ3.58: —Si(OCH₃ )₃(s)         -   2.92: —CF₂CH₂ CF₂-(quin)         -   2.12: —CH₂ CH₂CH₂-(tt)         -   1.74: —CH₂CH₂ CH₂-(m)         -   0.72: —CH₂CH₂CH₂ -(t)

¹⁹F-NMR (CDCl₃, 282.65 Hz):

-   -   −82.1:CF₃ CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—     -   −113.2:CF₃CF₂CF₂CF₂ CH₂CF₂ CF₂CF₂CF₂CF₂CH₂—     -   −115.6:CF₃CF₂CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂ CH₂—     -   −122.5:CF₃CF₂CF₂CF₂CH₂CF₂CF₂ CF₂CF₂CF₂CH₂—     -   −124.0 to −126.0:CF₃CF₂CF₂ CF₂CH₂CF₂CF₂CF₂ CF₂ CF₂CH₂—     -   −127.0:CF₃CF₂ CF₂CF₂CH₂CF₂CF₂CF₂CF₂CF₂CH₂—

COMPARATIVE EXAMPLE

In Reference Example 2, 30 g (0.08 mol) of C₆F₁₃CH₂CH═CH₂ was used in place of the terminal allyl compound, and the amount of the Karstedt's catalyst was changed to 31.6 g (0.1 mol % based on the terminal allyl compound), the amount of trichlorosilane was changed to 10.1 ml (0.105 mol), the amount of methanol was changed to 12 ml (0.30 mol), the amount of methyl orthoformate was changed to 7.7 ml (0.1 mol), and the temperature to react with trichlorosilane was changed to 60° C., respectively. As a result, 31.66 g (yield: 79%) of a transparent liquid terminal trimethoxysilylpropyl derivative was obtained.

CF₃CF₂CF₂CF₂CF₂CF₂CH₂CH₂CH₂—Si(OCH₃)₃

¹H-NMR (CDCl₃, 300.4 Hz):

-   -   δ3.63: —Si(OCH₃ )₃(s)     -   2.10: —CH₂ CH₂CH₂-(quin)     -   1.81: —CH₂CH₂ CH₂-(m)     -   1.74: —CH₂CH₂CH₂ -(t)

¹⁹F-NMR (CDCl₃, 282.65 Hz):

-   -   −82.0:CF₃ CF₂CF₂CF₂CF₂CF₂CH₂—     -   −115.6:CF₃CF₂CF₂CF₂CF₂CF₂ CH₂—     -   −123.1:CF₃CF₂CF₂CF₂CF₂ CF₂CH₂—     -   −124.0:CF₃CF₂CF₂ CF₂CF₂CF₂CH₂—     -   −124.8:CF₃CF₂CF₂CF₂ CF₂CF₂CH₂—     -   −127.3:CF₃CF₂ CF₂CF₂CF₂CF₂CH₂—

Reference Example 3

Substrate: Matsunami Glass (Preclean water edge polishing 57213)

Solution: 100 g of Vertrel, 0.1 g of sample, 40 mg of 0.05 M hydrochloric acid, and 5 ml of methanol

Coating conditions: spin coating, 0.5 g, 1000 rpm, 30 seconds

Drying conditions: 23° C., 50% RH

The following table shows the results of the measurement of the contact angle of each sample under the above conditions.

TABLE Contact angle (° ) No. Sample H₂O Hexadecane 1 Ref. Ex. 1 108 69 2 Ref. Ex. 2 108 69 3 C₆F₁₃CH₂CH₂Si(OEt)₃ 106 63 4 Comp. Ex. 106 73 5 C₈F₁₇CH₂CH₂Si(OEt)₃ 109 69 

1-2. (canceled)
 3. A carboxylic acid allyl adduct represented by the general formula: CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)CH₂CHICH₂OCOR′  [II] wherein n is an integer of 0 to 5, a is 1 or 2, and b is an integer of 0 to 3, and R′ is a C₁-C₃ alkyl group.
 4. A method for producing the carboxylic acid allyl adduct according to claim 3, the method comprising reacting polyfluoroalkyl iodide represented by the general formula: CF₃(CF₂)_(n)(CH₂CF₂)_(a)(CF₂CF₂)_(b)I  [III] wherein n is an integer of 0 to 5, a is 1 or 2, and b is an integer of 0 to 3, with carboxylic acid allyl R′COOCH₂CH═CH₂ having a C₁-C₃ alkyl group (R′). 